第3题: [单项选择]Hail is formed when a drop of rain is carried by an updraft to an altitude where ____ to freeze it.
A. is the air cold enough B. the air cold enough C. the cold enough air D. the air is cold enough 参考答案:D 答案解析:答案:D
分析:空格处是wherey引导的定语从句修饰altitude,只有D是完整句子。
翻译参考:当雨滴被上升气流带到一定高度,在此高度空气足够冷以使雨滴结冰,这时冰雹就形成了。